Beverage containers are used to hold both hot beverages (e.g., coffee) and cold beverages (e.g., soda). Unfortunately, hot beverages rapidly cool once placed in a typical beverage container. The use of a tight-fitting lid may inhibit cooling. However, a significant portion of the cooling is typically effected by heat transfer from the hot beverage, across the walls of the beverage container and, ultimately, to the ambient atmosphere.
Heat transfer across the walls of beverage containers has an opposite effect on cold beverages. Specifically, cold beverages warm over time, which may result in melting of the ice and, thus, unintentional dilution of the beverage. Furthermore, in humid environments, water droplets (i.e., condensation) tend to form on the external surface of poorly insulated beverage containers housing cold beverages. Such condensation may pool over time.
Furthermore, heat transfer across the walls of the beverage containers may significantly increase the surface temperature of the beverage container, which may render the beverage container too hot to comfortably handle, or may significantly decrease the surface temperature of the beverage container, which may render the beverage container too cold to comfortably handle.
Thus, efforts have been made to insulate the walls of beverage containers. Unfortunately, these efforts have encountered various obstacles. For example, polystyrene foam beverage containers provide improved insulation, but tend to be fragile and are not biodegradable. Environmentally friendly beverage containers, while more structurally robust than polystyrene foam containers, tend to provide only limited insulation.
Accordingly, those skilled in the art continue with research and development efforts in the field of insulated containers.